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In this thesis, bi-layered aerogel-plaster composite boards for thermal building insulation are produced. The influence of four design parameters of the bi-layered boards on their overall density, thermal conductivity, compressive strength and three-point bending strength was determined using a 24-1 fractional factorial design of experiments with the fraction of aerogel within an aerogel containing layer being varied between 35 and 70 vol% to lower the cost of the investigated boards and to retain a decent strength. The surfactant solution used to disperse the aerogel in the plaster mixture was found to cause cracking during drying of the boards above a threshold concentration. The influence of the surfactant solution on the setting behaviour of the plaster was characterized by monitoring the setting behaviour using electrical resistivity measurements. X-ray diffraction was performed on the hemihydrate powder as well as on the aerogel-containing layers of the finished boards. It showed that setting process was completed for the finished aerogel-gypsum boards and that the hemihydrate powder did not contain a fraction of anhydrite. Investigation of the fracture surfaces using scanning electron microscopy showed a change in gypsum crystal shape upon the addition of aerogel and surfactant solution. Fractional factorial analysis of the overall density, thermal conductivity, compressive strength and three-point bending strength showed that the thickness of the aerogel-plaster composite layer in the bi-layered boards was the most important factor for all properties. Furthermore, either the surfactant solution or the aliasing combined effect of thickness of the aerogel containing layer, had a significant effect on the thermal conductivity. The bending strength was found to be significantly decreased upon addition of aerogel granules.

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Abstract During the course of this master’s thesis, the deposition of a homogenous polymer layer on the surface of titanium (Ti) was investigated, which is capable of chemically anchoring bioactive molecules for antimicrobial applications, this way preventing post-surgery infections of orthopedic and dental implants. The deposition of the polymer layer was done using 3 (mercaptopropyl)trimethoxysilane (3 MPS) monomer precursor enriched with thiol functional groups via a dielectric barrier discharge (DBD) atmospheric plasma. Model proteins, bovine serum albumin (BSA) and bioactive molecules, deoxyribonuclease I (DNase I) were attached to the polymer layer through the thiol functional groups by creating double disulfide bonds with the cysteine amino acid sequence found in the peptides. The deposition of the biomolecules was done by classical dipping method and by alternating current electrophoretic deposition (AC – EPD), which is a state-of-the-art deposition technique. First, a trial-and-error approach was used to optimize the process parameters of the plasma activation (PA) and plasma polymerization (PP) processes. The surface properties of the processed samples were characterized by surface topography and surface wettability measurements. The final polymer layer was considered homogenous until a slight deviation in surface properties was observed. Following the optimization of the plasma treatment parameters, the polymer layer underwent additional characterization regarding its surface morphology and surface physio-chemistry. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) measurements showed a homogenous deposition of the polymer layer, with a thickness of ~ 35 nm. Fourier-transform infrared spectroscopy confirmed the presence of monomer related bonds. Next, the attachment of a model protein (i.e. BSA) was measured using adsorption kinetic measurements. The results of the assessment indicated that the adsorption of the BSA molecules was faster and lasted longer on the polymer coated samples compared to the non-coated ones. SEM images supported the results, which were obtained with the adsorption kinetic measurements as the protein layer was observed. Lastly, the enzyme activity of the DNase I coatings on Ti substrates deposited by AC – EPD was tested quantitatively. The superiority of the polymer coated samples was proved once again, showing a 20-fold difference in enzyme activity compared to the non-coated samples when using the dipping technique. While the polymer coated samples demonstrated enhanced capabilities in attaching biomolecules to the Ti substrate surfaces, the AC – EPD deposition was not entirely successful. Future optimization of the process parameters could focus on further optimizing the experiments to achieve a more effective antimicrobial coating on Ti.

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Ice, a ubiquitous natural phenomenon, often brings a negative impact on normal human life. Examples such as blade damages, traffic difficulties and power shortages caused by icing facilities are usually severe and even fatal to human lives. A widely accepted process to prevent the ice accumulation on materials is to cover them with passive coatings, which is popular due to its low costs and good feasibility. In order to produce coatings with reliable de-icing performance, it is essential to understand the mechanism of de-icing and what factors control the de-icing performance. As a method for studying the characteristics of nanoscale materials as well as seeking icephobic materials, molecular simulation has the advantages of convenience, high efficiency and low cost. Previous researches in this field usually focused on modelling and investigating the nucleation efficiency of ice on different substrates. However, most studies only focus on the behaviours of ice on specific substrate materials under static states, without discussing the dynamic behaviours between them and drawing a universal conclusion. Hence, in this study, molecular dynamics simulations produced by Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) were performed to investigate the general mechanism of making materials easier to remove ice, accompanied by the discussion of dynamic behaviours between the materials and ice. The first part of simulations was performed to explore the most stable ice orientation among basal face, prism face and secondary prism face. More simulations were carried out to understand the relationship between ice adhesion and wettability, including simulations with static substrates and substrates with moving atoms. Lastly, the influence of surface patterning is was discussed among line patterns and point patterns. The first part of simulation results shows that the basal face has the highest system energy, indicating that the ice should stay in the form of basal face as it is the most stable ice orientation. Thus, the following simulations are all carried on with ice in basal face. Subsequent simulations demonstrate that higher contact angles between substrates and water result in lower ice adhesion. Whether atoms move in the substrate does not have noticeable influences on the results of contact angle. On the other hand, a significant difference was witnessed in ice adhesion results, and a much larger strength was observed in the moving atoms substrate. Hence, simulations on a "static" substrate do not always represent the true behaviours between ice and materials. The Final part of simulations suggests that the geometry of patterns does not affect the ice adhesion behaviour. To sum up, based on the molecular dynamics simulation results produced by LAMMPS, materials with low hydrophobicity are thought to be better candidates for producing passive or de-icing coatings. Furthermore, atoms in it are better to have a strict interaction to restrict the moving of atoms as to mimic the "static" substrate.

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This thesis is in cooperation with H. Modarres who comes from Nanomanufacturing Research Group of University of Cambridge and the goal of this thesis is to provide a better understanding of nanomaterial manufacture process by playing a series of molecular dynamics (MD) simulations. H. Modarres et al. [1] successfully synthesized the sodium titanate nanorods (Na_2 Ti_3 O_7) wrapped by reduced graphene oxide sheets (rGO) and then achieved TiO_2 nanorods with the rGO wrapping around it in the experiment which are used as the anode material of the lithium ion batteries. The scrolls own the interior cavities providing an ideal ion-transfer channel for the lithium ion transport. However, the formation mechanism of such scrolls is still unknown while MD simulation can provide a good way to study the nanoscale formation process. Therefore, nanoscale modelling of the wrapping process of graphene by titanium dioxide nanorods is studied in this thesis. In the first part of the simulation, Material Studio (MS) is used to simulate Na_2 Ti_3 O_7 nanorods with graphene sheets system and since no one hasn’t been use MS to model Na_2 Ti_3 O_7 nanorods so the force field validation for Na_2 Ti_3 O_7 nanorods is reviewed. After that, the TiO_2 nanorods with graphene sheets system is mainly investigated by LAMMPS. Specifically, chapter 6 elaborates on the wrapping process of graphene sheets with different crystal structure of TiO_2 nanorods, chapter 7 investigates the influence of different lengths of TiO_2 nanorods on the wrapping process with nanorods having an anatase structure, chapter 8 explains the wrapping process of multilayer graphene sheets with anatase nanorods and the bending stiffness of multilayer graphene sheets is characterised. Chapter 9 focuses on the study of wrapping process of defective graphene sheets with anatase nanorods. Finally, the competition of the interaction energy between the nanorods and the graphene sheets is found to play a significant role in the wrapping process. Adjusting the parameters of the nanorods like length or radius can have an effect on the wrapping process. For defective graphene sheets, the wrapping process is not only controlled by the interaction energy but also affected by the physical obstacles.

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'Everything flows and nothing abides'. This quote from the Greek philosopher Heraclitus is the motto of a branch of science and technology called 'dynamic wetting'. To be specific, when a liquid is placed in contact with a solid substrate, the liquid front advances spontaneously towards equilibrium due to the out-of-balance Young's force. As the liquid spreads, the dynamic contact angle relaxes to equilibrium state. In this framework, this doctoral dissertation discusses the physico-chemical aspects of the wetting dynamics of liquid polymers in contact with flat substrates and fibers. Since the wetting behavior of molten drops of thermoplastic polymers is important in the processing of fiber-reinforced polymer composites and the ability of classical theories of dynamic wetting like the hydrodynamic approach (HD) and molecular-kinetic theory (MKT) to model molten polymers is unknown, we therefore investigated the spreading dynamics of polypropylene (PP), poly(vinylidene fluoride) (PVDF) and maleic anhydride-grafted polypropylene (MAPP) on flat glass substrates between 200°C and 260 °C. These polymers were chosen based on the fact that they have different physicochemical interactions with glass. The viscosities and surface tensions of these molten polymers were obtained by rheological measurements and the pendant drop method at different temperatures. Besides, the chemical interaction between MAPP and the glass substrate was validated by performing Fourier-Transform Infrared Spectroscopy-Attenuated Total Reflection experiments. In terms of spreading dynamics, it was evidenced that both HD and MKT showed excellent fitting agreements with the experimental data and the corresponding fitting parameters were meaningful, indicating that both models are relevant here. This triggered a question about the identification of the dominant energy dissipation channel for spreading dynamics of molten polymers on a flat substrate. Next, a fiber substrate was used to uncover the dominant channel of dissipation for liquid polymers as the fiber geometry enhances the difference between the HD and MKT and therefore helps to distinguish between the dissipation regimes. Two types of polydimethylsiloxane (PDMS) with kinematic viscosities of 5 mm2/s (PDMS5) and 500 mm2/s (PDMS500) were selected as model liquids and a series of mixtures with different mass ratios were prepared. The dynamics of the capillary rise of PDMS mixtures on a fiber were studied, and the MKT and HD regimes were distinguished by their scaling laws. Besides, the MKT/HD transition of the PDMS mixtures was compared to the one of pure PDMS liquids. The MKT/HD transition of PDMS mixtures moved to a higher viscosity regime and we hypothesized that a surface segregation mechanism controlled this shift. Finally, the transition interval between the MKT and HD regimes was further explored. Two types of PDMS liquids with kinematic viscosities of 20 mm2/s (PDMS20) and 50 mm2/s (PDMS50) at room temperature were selected. The capillary rise of these two liquids around a fiber was studied at different temperatures and the existence of a sharp transition between the MKT and HD regimes was demonstrated. Within this sharp transition region, the fiber roughness played an important role in the identification of the dominant channels of dissipation. Beyond this sharp transition region, the identification of the dominant channels of dissipation was not affected by the fiber roughness. A liquid rim ahead of the apparent contact line was observed and proposed to account for the viscosity dependence of the channels of dissipation.